In an RF analog IC, composing a circuit which includes a high performance capacitive element, a resistive element, and an inductor element becomes an important factor. Specifically, a decrease in the parasitic resistance and parasitic capacitance has been required due to the need for high-speed performance, low power consumption, and space-saving of a system.
In such a situation, attention has been paid recently to a MIM (Metal-Insulator-Metal) capacitor as a capacitive element which enables a reduction in the parasitic resistance and parasitic capacitance.
As disclosed in JP-A No. 2002-329790 and JP-A No. 2005-311299, in a MIM capacitor, a film made of the same material as the aluminum interconnect is used for a lower electrode of the capacitive element in order to decrease the parasitic resistance. The aluminum interconnect generally has a film structure where the upper face of a film including aluminum as a main component is covered with a barrier film, and a MIM capacitor in JP-A No. 2002-329790 has a lower electrode where the upper face of an aluminum film is covered with a thin barrier film (55 to 85 nm) consisting of a stacked film of a titanium film and a titanium nitride film. Moreover, a MIM capacitor in JP-A No. 2005-311299 has a lower electrode where the upper face of an aluminum film is covered with a thin barrier film (50 nm) consisting of a titanium nitride film.
Furthermore, in a MIM capacitor, the capacitive dielectric film has been made thinner in order to increase capacitance, and improvement of the reliability of the dielectric voltage of the capacitive dielectric film which is made thinner also becomes an important problem. JP-A No. 2002-43517 was proposed as a technology to solve such a problem.
In JP-A No. 2002-43517, after the roughness of the surface of the lower electrode is planarized by performing ion irradiation or plasma irradiation on the surface of the lower electrode, a capacitive dielectric film is deposited. Therefore, it is described that making the film thickness of the capacitive dielectric film can be compatible with improvement of the dielectric voltage thereof.